I have had as many as 7 chromis in my tank and, for a while, they swam in the open all around the upper 1/3 of the aquarium. A couple decided the grass was greener on the other side of the glass so jumped to their eventual death. The remaining 5 just hang out in a corner of the aquarium and never explore the aquarium any more except to come out and eat. All the other fish (anthias, tangs, hawkfish, rabbit fish, bannerfish) swim all over. I love the idea of a shoal of chromis but these five make me sometimes wish they would follow their former brethren into the abyss outside the glass. Anyone else have issues with reclusive chromis?

Green chromis aren’t the boldest of all fish, but they will typically spend most of their time at least moving in and out of open water.

If they’re not coming out, it’s because somebody in the tank is not letting them come out. Might also explain the jumpers.m

(of course, this is just a guess)

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Hope this is the case for you. Chromis will eventually kill off one another until there's only 1 left unless there's a predator/bully in tank which keeps them shoaling for protection. I've noticed when chromis are in a peaceful tank, they swim all over and end up killing each other bc they no longer need to shoal for protection. Also, I recommend getting a lid.